The goal of the proposed research is to provide fundamental information on the functional organization of that region of the lateral-posterior (LP)-pulvinar complex which receives a direct projection from the superior colliculus. This area of the posterior thalamus has often been suggested to serve as a relay by which visual information from the midbrain is conveyed to cortex. The tectorecipient zone of LP-pulvinar has been studied primarily with anatomical methods, and thus far little is known about its function. Accordingly, this project will: (a) analyze receptive field properties of single neurons in immobilized, as well as in behaving animals, in order to determine what type of visual information is processed by cells in the tectorecipient zone; and (b) assess the contributions of the tectal input to the visual response characteristics of LP-pulvinar neurons by reversible cooling of the superior colliculus. The results of these neurophysiological experiments will be related to the collicular projection as defined by axoplasmic methods. Completion of this project will enhance our understanding of the role of extra-striate visual system in visual processing.